Now to a story about the power of social media and how Facebook helped save a little girl's eyesight after her mom posted a snapshot of her 3-year-old daughter. ABC's Mara schiavocampo is in social square and has the story. Mara. Reporter: Good morning, Amy. You said it. The power of social media on full display. That picture got more than just a few likes, it also helped that mom get crucial medical advice catching a rare eye disorder in just the nick of time. When Tara Taylor posted this photo of her daughter on Facebook, she had no idea that simple action would change her daughter's life. Facebook ironically has been such a blessing in our life. Reporter: The picture of 3-year-old Rylee got some "She's so cute" posts but her friend Stacy Carter noticed more than her adorable saw and saw this white glow in Rylee's left eye. Stacy said her friend's son had an eye disease with the same symptoms. Immediately, you know, sent her a message saying, hey, it could be nothing or, you know, there could be something really wrong with Rylee a eye. It was in the evening. Doctors' offices were closed. We just kind of felt helpless there was nothing we could do. We were a little scared just because, you know, we didn't know what it was. Reporter: Sure enough her keen-eyed friend was right and doctors confirmed she was going blind in her left eye from coats' disease. Coats' disease is a rare eye disease that's caused by an abnormal leaking of blood vessels behind the eye which can cause blindness. Reporter: Doctors say Rylee's case was advanced but after two surgeries they've seen some improvement in her vision and if the disease was spotted any later Rylee likely would be permanently blind in her left eye. Tara says she was shocked because there were no warning signs. We never noticed any symptoms that would indicate that we should go to the eye doctor. She actually can sit very far from the TV. She will look at her books. She does every activity that her sister does and no differently. Reporter: The family thankful that sharing on Facebook led to an eye-opening discovery. And here in the social square this time line shows just how quickly this developed from the time Tara posted that picture to the time she got that medical tip, just one hour. They went to the doctor the next day and, you know, doctors say that something like this normally isn't diagnosed until it starts to affect both eyes.

This transcript has been automatically generated and may not be 100% accurate.

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